1. Technical Field
Various embodiments generally relate to a semiconductor apparatus, and more particularly, to data reception of a semiconductor apparatus.
2. Related Art
A semiconductor apparatus includes a data receiving unit to receive data from an external device. The current semiconductor apparatus operates in synchronization with a clock signal, in order to perform an operation at high speed. Therefore, the data receiving unit also latches data applied from the external device in synchronization with the clock signal.
Referring to FIG. 1, general data receiving unit 1 includes a plurality of receivers (not illustrated) configured to latch a plurality of external data DATA in synchronization with a data latch clock signal CLKOUT and output the latched data as a plurality of internal data DATA_TX, respectively.
Recently, a DDR (Double Data Rate) synchronous semiconductor apparatus has been used to improve operation speed. When the DDR scheme is used, data are latched at falling edges as well as rising edges of a clock signal. According to the DDR scheme, the data receiving unit 1 may latch the external data DATA at falling edges as well as rising edges of the data latch clock signal CLKOUT, thereby quickly receiving the data.
Meanwhile, the semiconductor apparatus must accurately latch the external data DATA in order to normally operate. For this operation, the phase of the data latch clock signal CLKOUT must be controlled to accurately latch the data. Furthermore, the internal data DATA_RX received according to the DDR scheme must be aligned depending on the purposes of data (or command) applied from the external device, regardless of whether the data were latched at rising edges or falling edges of the data latch clock signal CLKOUT.